(defmacro n (&rest r)
 )


;=================================================
; task: to get a solution(s) of square equation
;
(n defsolution solve-square-equation (arguments)
 (extract-arguments (a b c) :from arguments)
 (require-to-be (type-of a b c) float-compatible)
 (introduce-variable :scope local :type (type-of a b c))
 (let (= d (- (square b) (* 4 a c))))
 (if (< d 0) (return-nothing))
 (if (= d 0) (return-one-solution (/ (- b) (* 2 a))))
 (if (> d 0) (return-solutions (/ (- d b) (* 2 a)) (/ (- (+ d b)) (* 2 a))))
 )

(n use-solution-sample (context)
 (let results (solve-square-equation :a (content-of edit-box-a) :b b :c c))
 (if (empty results))
 )
